ABSTRACT Converging evidence documents moderate to high rates of sexual violence against youth. The 2011 Youth Risk Behavior Survey, a national survey of students in grades 9-12, found a lifetime reported prevalence for unwanted physically forced sexual intercourse of 11.8% for girls and 4.5% for boys (Centers for Disease Control and Prevention, 2012). In addition, physical or verbal sexual harassment is extremely common in schools among adolescents, with one national study reporting that 57% of boys and 50% of girls reported sexually harassing a peer. Despite the importance of this public health problem, sexual violence prevention has a limited evidence base. Equally challenging, most school-based anti-violence programs have focused on individual types of aggression, typically physical aggression occurring within relationships (Leff, Power, Manz, Costigan, & Nabors, 2001). At present few programs systematically address broader social-ecological factors such as school-wide norms and youth-adult connectedness that research identifies as major drivers of SV (Basile, Espelage, Rivers, McMahon, & Simon, 2009). To address this gap, this application proposes a large- scale RCT evaluation of Sources of Strength to evaluate for sexual violence perpetration outcomes. Sources of Strength is an evidence based program for youth suicide that trains student key leaders to strengthen social connectedness and healthy norms school-wide (Wyman et al., 2010) and is listed on the National Registry of Evidence Based Programs and Practices (NREPP). This project will expand the existing evidence base by evaluating Sources of Strength for sexual violence outcomes, which has never been done before. Twenty-four high schools will be recruited and stratified (rural or urban) and randomly assigned to one of two conditions: (a) immediate Sources of Strength intervention, (b) wait-list for Sources of Strength Implementation after 16 months. A representative sample of each school (grades 9-11, in total n = 7200) will be enrolled for repeated longitudinal assessment to assess SoS impact as well as moderators and mediators of its efficacy. The intervention will be rolled out between spring 2017 and spring 2020 with cohorts receiving the intervention for 16 months and completing a total of four assessments. This study is highly innovative and could have substantial public health impact by targeting shared risk and protective factors to demonstrate impact on multiple forms of violence. This approach builds on the call to evaluate `cross over' effective of preventive interventions (Reider & Sims, 2016) in order to identify common prevention pathways to multiple health behavior problems. A strength of our proposed study is measurement of factors across student (behaviors, attitudes, norms), interpersonal (peer social networks), and school-level (school climate based on aggregate school staff reports).